Conventionally, there is known a valve timing control apparatus including a restricting mechanism provided separately from a locking mechanism for maintaining a relative rotational phase of a driven-side rotary member relative to a driving-side rotary member to a predetermined phase (locking phase), the restricting mechanism consisting of a restricting recess portion formed in the driven-side rotary member and a restricting member provided in the driving-side rotary member and capable of projecting/retracting relative to the restricting recess portion.
For instance, Patent Document 1 discloses a restricting mechanism consisting of an engaging pin 91 (restricting member) and an engaging groove 28 (restricting recess portion). With such arrangement, the locking mechanism can be operated after the relative rotational phase of the driven-side rotary member relative to the driving-side rotary member is restricted within a predetermined range, so that the locked state can be realized more easily.
Further, with the valve timing control apparatus described in Patent Document 1, there is adopted an arrangement that fluid is discharged from the advanced angle chamber and the retarded angle chamber when the relative rotational phase is not at the locking phase at the time of startup of the engine. This arrangement is provided for realizing the locked state during rotation of the engine as a condition that positively allows relative rotation of the driven-side rotary member relative to the driving-side rotary member immediately after engine startup.